Vanes of low-pressure turbines have been made of metal and are generally soldered together first to form segments of three or six vanes and then to form the annular ring. For investigations of aerodynamic dimensioning of the profile of the vane blades as well as for incorporation in an actual gas turbine drive mechanism, a number of vane segments are secured together to form a ring of blades in which individual vane segments are not rigidly connected to one another in order to accommodate thermal expansion. The vanes are fastened by their outer platforms in a drive housing and are detachably connected to one another at their inner platforms by metal clamps or the like. By clamping the vanes at the inner platforms, the vibration behavior of the vane blades is improved. The use of clamps as additional components, however, has the disadvantage of more extensive assembly and higher costs.
For calibrating the aerodynamic dimensioning process and for rapid determination of test data for alternately measuring pressure, velocity and flow quantity, vanes made substantially of carbon-fiber-reinforced plastics are utilized and are tested in so-called aerodynamic "cold" test stands. Such vanes can be produced considerably more rapidly and at lower cost than corresponding vanes made of metal and thus are preferably utilized in these investigations. Vanes of plastic are loaded in the test stand at considerably lower temperatures (approximately 130.degree. C.) compared to actual operation, but are subjected to forces of the same order of magnitude as in the actual drive turbine.
It is thus a problem to adopt the geometry of the outer and inner platforms of the vanes made of metal for those made of plastic, since the latter cannot withstand the high loads produced by the actual gas forces. Gluing or bonding together three or six vane elements into individual vane segments, from which the vane ring is formed has only slightly met this problem. Similarly, securing the vane elements by means of bolts at lateral front surfaces of the inner and outer platforms has not proven effective because the amplitude of vibration of the vanes was too high and led to breakage of the vanes.